is there a specific rule on temporary bonuses somewhere? mainly i am wondering if casting eagle's splendor would increase the amount of lay on hands a paladin would get each day. it specifically says no to getting extra spells, but nothing about special abilities.

No, temporary bonuses never increase your daily abilities. Below are three sections relevant to charisma increases. They are all on page 554 and 555 of the CRB.

CRB p554 wrote:

Ability score increases with a duration of 1 day or less give only temporary bonuses. For every two points of increase to a single ability, apply a +1 bonus to the skills and statistics listed with the relevant ability.

And for Charisma:

CRB p555 wrote:

Charisma: Temporary increases to your Charisma score give you a bonus on Charisma-based skill checks. This bonus also applies to any spell DCs based on Charisma and the DC to resist your channeled energy.

Contrast with permanent:

CRB p555 wrote:

Permanent Bonuses: Ability bonuses with a duration greater than 1 day actually increase the relevant ability score after 24 hours. Modify all skills and statistics related to that ability. This might cause you to gain skill points, hit points, and other bonuses. These bonuses should be noted separately in case they are removed.